Method of making open-ended thermoplastic belting

ABSTRACT

A system and method of making an open-ended, reinforced, layered belt having a profile layer, a top layer material, and tensile cords fully encapsulated there between. The method includes engaging portion of the profile layer on a rotatable cylindrical mandrel with an engaging roller, disengaging with a take-off roller, and applying and fusing the cords to the profile layer at a desired cord spacing there between. The cord may be fused by melting the profile layer surface with a heated plow and/or with heated cord. The cord is then covered with the top layer material in a lamination step involving heating to melt at least a portion of the top layer and pressing it to fuse it to the reinforced profile layer. Lamination may be done downstream or directly on the mandrel.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to a system for making open-endedbelting reinforced with a tensile cord layer that is totallyencapsulated, without use of mold flights or noses.

2. Description of the Prior Art

Conventional processes of continuous extrusion-forming of thermoplasticelastomer (“TPE”) or thermoplastic urethane (“TPU”) reinforced beltprofiles utilize a rotatable molding wheel which is supplied with amolding band (usually of flexible steel) wrapping around about half ofthe circumference of the molding wheel to form a rotating moldingchamber into which cords are fed along with extruded belt material. Formaking toothed belts, the molding wheel has teeth with winding noses orflights on the mold teeth to support the reinforcing cord and thus setthe pitch line differential (“PLD”) of the belt. The use of noses orflights results in cord exposure to the environment in the land areabetween each tooth of the finished belt. The lack of cord support on apulley in the exposed nose region also contributes to failure of thetensile member (especially for aramid cords) when the belt is subjectedto dynamic flexing. An example of a conventional process using windingnoses is disclosed in U.S. Pat. No. 3,880,558 to Breher et al.

For steel wire tensile members, the cord exposure necessitates special(expensive) corrosion-resistant steels or coatings, such as a zinccoating applied to each individual filament. Post processing steps canbe added to fill in the nose regions with additional thermoplasticmaterial to protect the cords, but at additional effort and expense.

Another method of eliminating the nose region includes a speciallydesigned dual-nozzle extruder die which places a layer of thermoplasticon the mold teeth before the cord arrives thereon, as also disclosed inU.S. Pat. No. 3,880,558 to Breher et al. However, this method does notmake it easy to control the belt PLD.

Another method of eliminating the nose region includes inserting a toothcovering fabric onto the mold before the cord is placed thereon asdisclosed in U.S. Pat. No. 4,515,743 to Breher. This method adds fabricexpense and changes the nature of the belt surface, which may notnecessarily be desirable.

Another method suited for making flat belts is disclosed in U.S. Pat.No. 6,966,763 to Goser et al., in which two layers of material areapplied by two separate extrusion stations.

Mention is made of the applicants' co-pending U.S. application Ser. No.13/715,989 filed on Dec. 14, 2012, titled “Apparatus and Method forMaking Endless Reinforced Belts,” claiming the benefit of provisionalapplication 61/570,814 filed on Dec. 14, 2011, the entire contents ofwhich are hereby incorporated herein by reference.

Conventional extrusion systems using some type of cross head die withtensile cords passing through have practical limitations with respect toproducing wide belt sections. Belts wider than about two feet are notpractical.

What is needed is an improved method of making continuous, open-ended,reinforced thermoplastic, profile belting, capable of much wider beltwidths.

SUMMARY

The present invention is directed to systems and methods which providecontinuous, open-ended, reinforced thermoplastic, profile belting withfully encapsulated cords and accurately controlled PLD, and whichprovide the capability of making very wide reinforced belting. Thepresent invention also provides systems and methods which providebelting without nose regions and with improved flex fatigue resistance.

The invention is directed to a system for making an open-ended beltshaving a profile layer having a top side and having a belt profile onthe opposite side, a top layer material suitable, and tensile cordsembedded there between. The belt is made on an apparatus including arotatable cylindrical mandrel having a mandrel profile complementary tothe belt profile and an engaging roller positioned adjacent the mandrelfor pressing the profile layer onto the mandrel inducing wrappedengagement of the profile layer on a wrap portion of the mandrel duringrotation of the mandrel. The apparatus may include a take-off rollerpositioned adjacent the mandrel more or less opposite the engagingroller to disengage the profile layer from the wrap portion of themandrel during rotation of the mandrel. The wrap portion may occupy from45 to 315, or 90 to 300, or preferably, 180 to 270 degrees of themandrel circumference. When the belt is a toothed belt, the profilelayer has a plurality of teeth, and the mandrel has grooves adapted tomate tightly with the teeth.

The apparatus further includes a cord applicator positionable adjacentthe mandrel to apply the tensile cords to the profile layer within thewrap portion at a predetermined cord spacing so that the cords arefirmly attached to the profile layer before disengagement of theresulting reinforced carcass portion from the wrap portion of themandrel. The apparatus also includes a laminator to apply and attach thetop layer material to the reinforced carcass to fully cover orencapsulate the cords and complete the belt.

According to an embodiment of the invention, the laminator may includetwo laminating rollers downstream of the mandrel defining a nip therebetween to press the top layer onto the carcass therein, and a laminateheater may be positioned near the nip to provide melting energy to atleast one surface of one or both of the top layer material and thecarcass for fusing them together.

According to another embodiment of the invention, the laminator mayinclude a laminating roller adjacent the wrap portion of the mandrel,defining a nip between the mandrel and the laminating roller; and alaminate heater may be positioned to provide melting energy to at leastone surface of one or both of the top layer material and the carcass.

According to another embodiment of the invention, the laminator mayinclude a molding band instead of the aforementioned laminating rollerwith a portion of the band wrapped around a portion of the otherlaminating roller or the mandrel and thus defining a laminating cavitythere between. Again, a laminate heater may be positioned to providemelting energy to at least one surface of one or both of the top layermaterial and the carcass before they enter the cavity to be pressedtogether therein. Alternately, the top layer material may be completedmelted or supplied in liquid form and metered into the cavity tosolidify and/or cure.

According to an embodiment of the invention, the cord applicator mayinclude a heated plow adjacent the wrap portion for plowing at least oneheated groove of predetermined depth in the profile layer, and a cordlaying guide positioned to lay a cord into the heated groove to fuse thecord to the profile layer. The cord applicator may press the cords lessthan fully into the profile layer.

The cord applicator may include a multiple cord laying guide for layingdown all the desired cords side by side at some desirable cord spacingacross the entire width of said belt simultaneously, the profile blademay be adapted to form multiple grooves for simultaneously laying andfusing all the cords onto the profile layer.

The cord applicator may include a pair of rotating, grooved, electroderollers for electrically heating the portion of a conductive tensilecord trained there between, and for laying down and fusing saidconductive tensile cord onto said profile layer. The cord applicator mayinclude multiple pairs of rotating, grooved, electrode rollers forelectrically heating the portion of each conductive tensile cord trainedthere between, and for laying down and fusing the conductive tensilecords at the desired cord spacing all at once.

The materials may be thermoplastic elastomers. The top layer and profilelayer may be of the same material or two different materials. In otherembodiments, the laminator may cast a liquid, curable resin for the toplayer. The top layer may be a thermoset or thermoplastic material.

The invention is also directed to a method of making an open-ended,reinforced, layered belt including the steps of: (i) training aplurality of parallel tensile cords on a portion of a smooth, rotating,cylindrical mandrel, the portion including a cavity defined between themandrel and a molding band or a gap defined between the mandrel and alaminating roller; (ii) extruding a top layer material onto the cordsand metering it into the cavity defined between the mandrel a moldingband or into the gap defined between the mandrel and a laminatingroller; thereby forming a carcass comprising the cords embedded at onesurface of a film of the top layer material; (iii) training the carcasson a portion of a profiled, rotating, cylindrical mandrel having aprofile complementary to a desired belt profile, the portion including acavity defined between the profiled mandrel and the molding band or agap defined between the mandrel and the laminating roller, and the onesurface facing the profiled mandrel; and (iv) extruding a profile layermaterial onto the profiled mandrel between the carcass and the mandrelsurface and metering it into the cavity or into the gap; thereby formingthe belt comprising the cords embedded between the top layer materialand the profile layer material.

The foregoing has outlined rather broadly the features and technicaladvantages of the present invention in order that the detaileddescription of the invention that follows may be better understood.Additional features and advantages of the invention will be describedhereinafter which form the subject of the claims of the invention. Itshould be appreciated by those skilled in the art that the conceptionand specific embodiment disclosed may be readily utilized as a basis formodifying or designing other structures for carrying out the samepurposes of the present invention. It should also be realized by thoseskilled in the art that such equivalent constructions do not depart fromthe scope of the invention as set forth in the appended claims. Thenovel features which are believed to be characteristic of the invention,both as to its organization and method of operation, together withfurther objects and advantages will be better understood from thefollowing description when considered in connection with theaccompanying figures. It is to be expressly understood, however, thateach of the figures is provided for the purpose of illustration anddescription only and is not intended as a definition of the limits ofthe present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and form part ofthe specification in which like numerals designate like parts,illustrate embodiments of the present invention and together with thedescription, serve to explain the principles of the invention. In thedrawings:

FIG. 1 is a schematic representation of a belt-making system accordingto an embodiment of the invention;

FIG. 2 is a schematic representation of view A-A of the belt-makingsystem of FIG. 1;

FIG. 3 is a partially fragmented perspective view of a belt made by thesystem of FIG's 1 and 2;

FIG. 4 is a schematic representation of a portion of a belt-makingsystem according to another embodiment of the invention;

FIG. 5 is a schematic representation of a portion of a belt-makingsystem according to another embodiment of the invention;

FIG. 6 is a schematic representation of a portion of a belt-makingsystem according to another embodiment of the invention;

FIG. 7 is a schematic representation of a portion of a belt-makingsystem according to another embodiment of the invention; and

FIG. 8 is a schematic representation of a portion of a belt-makingsystem according to another embodiment of the invention.

DETAILED DESCRIPTION

The invention provides a method and apparatus for manufacture of openended belts made of an elastomeric matrix in which tension members areembedded in a longitudinal direction. Such belts can be toothed belts,flat belts, multi-v-ribbed belts, conveyor belts and similar products.The process is particularly useful for making toothed belts whichrequire precise control of the tooth spacing or “pitch.” The elastomericmatrix can be a thermoplastic polyurethane (TPU) or any other suitablethermoplastic elastomer (TPE). The process may also be adapted forcastable or thermoset resins or for a vulcanized rubber matrix. Thematrix may be a combination of materials, such as a laminate or blend.The matrix material(s) may include any number of desirable ingredients,including for example, anti-oxidants, anti-ozonants, UV stabilizers,anti-microbial additives, process aids, softeners, fillers, frictionmodifiers, foamers, and the like.

The tension members typically consist of cords, yarns, fibers orfilaments of steel, but could be glass, aramid, carbon, polyester,polyamide, basalt, or other suitable materials or hybrids thereof. Ayarn is a bundle of fibers, filaments or wires and may be twisted orcabled. A cord is a twisted, braided, or cabled yarn or bundle of yarnsand may be treated for adhesion or handling purposes. The terms wire andcable are often used in connection with metal cords or metal tensionmembers. Herein, “cord” or “tensile cord” will be used to refer to alltypes of tension members. Fabric layers or other non-typical types oftensile reinforcements may also be used in conjunction with yarn bundlesor instead of more typical cords, such as tire cord, open weave scrims,woven fabrics, or nonwoven fabrics, or the like.

In the following, for example, a process is described to make a toothedbelt out of thermoplastic polyurethane with steel cord as tensionmember, using the method and apparatus of the invention. It should beunderstood that the invention is not limited to these exemplarymaterials or belt types.

Toothed belt 20 in FIG. 3, according to an embodiment of the invention,includes three primary components: a base layer or profile layer 1,tension member 7, and top layer 10. One or both surfaces couldoptionally include a woven or non-woven fabric, plastic film, or othersurface treatment. The profile layer and top layer could be the samematerial or could be two different thermoplastic materials. The profilelayer and/or top layer could be laminated from a plurality of layers ofone or more materials or thermoplastic materials. The reinforcement,whether cord or fabric, could be applied to the top layer

Profile layer 1, may be made of continuous extruded TPE or TPU havingteeth, or other desired belt profile, on one side and a flat surface onthe opposite side. The profile layer may be formed by known methods ofextrusion forming or molding, such as the methods disclosed in U.S. Pat.No. 4,251,306, which utilize a molding wheel and molding band adjacentabout half of the circumference of the molding wheel to form a rotatingprofile molding chamber into which the profile material is extruded forcontinuous shaping. It should be understood that such forming processesmay be implemented without any embedded cord for the purposes of thepresent invention. Thus, the present profile layer may be formed muchmore quickly and efficiently than prior methods wherein a belt is formedwith cord embedded therein. Moreover, the belt profile formed on theprofile layer may be formed without the usual indentations or defects ofprior methods because flights or noses are not required for cordsupport. If desired the profile layer may include a textile layer or afilm on the tooth surface for wear resistance, noise improvement orother purpose. Suitable textiles include woven, knitted and nonwovenfabrics, for example. The final thickness of the profile layer isselected to allow full or partial embedding of the tension member at apredetermined pitch line differential (“PLD”). PLD is a measure of thethickness of the belt under the cord line, and is defined as thedistance from the belt surface in the land region to the cord centerline, as indicated in FIG. 3. The land region 18 is the thin section ofthe belt located between any two adjacent teeth 21.

Tension member 7 is typically made of continuous filaments twisted intoa cord and typically may have an adhesive coating to bond with theelastomeric matrix material(s). Tension member 7 is parallel to the beltedges. Two or more different cords may be placed in the belt side byside simultaneously. For example, one kind of cord, or two or more cordsof equal or opposite twist (i.e., S and Z twist) may be used as thetension member. The tension member may be exposed at the side of thebelt if the belt is cut lengthwise in the location of cord. Preferably,the tension member is fully embedded in the elastomer matrix withoutexposure at either side. Any suitable type of cord may be used. Anadhesive coating may be applied to the cord prior to cord laying in aseparate operation or to the cord or profile layer during cord laying inan integrated coating operation before the cord contacts the elastomericmatrix material(s).

Tension member 7 is applied and fused to profile layer 1 in acontinuous, cord application process that will be described in moredetail below. The resulting reinforced profile layer 27 is called the“carcass” or “reinforced carcass” herein. It requires the addition oftop layer 10 to make completed belt 20. It should be noted that theapplication of the cord to the profile layer is carried out on an openmandrel without use of a molding band.

Top layer 10 is typically made of a continuous TPE or TPU sheet ofeither the same material as the profile layer or a different material ordifferent formulation. For example, the profile layer may be made of arelatively stiffer material for carrying high tooth loads, while the toplayer may be of a relatively softer material for higher flexibility,different coefficient of friction and/or for reduced noise and/or forreduced cost. The thickness of the top layer may be selected to completethe embedding of the tensile member and have a desired amount ofadditional material over the cord in the belt. The top layer preferablymay have about the same width as the profile layer. The processing ofthe top layer in preparation for laminating may be off-line byconventional extrusion through a suitable die for a smooth top layer. Ifsome secondary profile or texture is desired on the back side of thebelt, then a process such as used for the profile material may insteadbe used to make the top layer. Similarly as for the profile material, atextile cover may be applied to the top layer during formation if such acover is desired for the finished belt to modify appearance, or toreduce friction and/or noise. The top layer 10 may be identical to theprofile layer 1, for example applied with teeth protruding from the topof the belt to make a dual-tooth belt, with teeth either staggered oraligned.

The lamination process is typically made using heat input to thelaminating surfaces at a heating rate such that, shortly before thenip-line between two laminating rolls, only the contact surfaces of thereinforced carcass and the top layer are molten, while the bodies ofthese materials still remain solid and keep their shape. Temperaturecontrol of the laminating rolls is also important in combination withthe rotation speed of the mandrel to insure sufficient heat on all threematerials (lamination material, cord and profile material) for a goodbonding and adhesion result. While going through the nip betweenlaminating rolls, the materials are pressed firmly together to avoid airentrapment and to provide immediate bonding of all three materials(cord, top layer, and profile layer). The heat input to the materialsurfaces entering the laminator nip may be provided by hot air blowerproviding heat and airflow, or by infrared radiation, or by a hot knifeor laser, or by combinations of heating means. Alternately, thelamination may utilize a pressure or molding band wrapped or placedaround a portion of a mandrel to provide a longer time period for fusingthe layers together than possible in a nip between two rollers.Alternately, the top layer can be extruded or metered into the spacebetween carcass and molding band, when a molding band is used. Alamination roll in any of the embodiments could have a surface textureor pattern in order to introduce a desired texture to the top layer,i.e. to the backside of the belt.

According to embodiments of the invention, the manufacturing processincludes the following steps using the apparatus as shown in FIG's 1 and2.

The profile layer 1 having the desired belt profile on one side isprovided in the desired length and width from spool 9. By “belt profile”is meant a belt surface configuration adapted to engage a pulley orsprocket in driving relation thereof in a belt drive system. In afriction driven belt drive system, for example, the belt profile may beflat, or V-shaped, or multi-v-ribbed, while in a synchronous or positivedrive system, the belt profile may be a series of evenly spacedtransverse teeth or angled or helical teeth. The present invention isparticularly advantageous for making toothed belts for positive drivesystems, which require close tolerances on the tooth shape and pitch andthe belt pitch length for proper meshing with toothed pulleys.

The profile layer 1 is then fed around engaging roll 4 onto mandrel 2 asshown in FIG. 1. Thus, profile layer 1 is wrapped around a portion ofmandrel 2, engaging the profile layer with the complementary moldprofile of the mandrel. Two smooth engaging rollers 3 and 4 may be usedto hold the carcass in engagement with the mold profile during mandrelrotation. These rollers are “positionable,” meaning they can be moved toa desired position to accommodate different material thicknesses,different pressure requirements, and the like. They are “adjacent” ornear the mandrel, meaning in close proximity to, or even touching themandrel or the belt materials being engaged on the mandrel, thusrotating in synchronization together. The arrows show the direction ofrotation of mandrel 2, and the direction of the other rollers andmaterials follow. The portion of the mandrel bounded by the two engagingrolls and on which the profile layer is wrapped is called the “wrapportion” or “engagement portion” of the mandrel herein. The portion ofthe profile layer, carcass or belt wrapped on the mandrel is likewisethe wrap portion 1 a or engagement portion thereof. In FIG. 1, the wrapportion is shown extending from about the seven o'clock position, thelocation of engaging roll 4, to about the two o'clock position, theposition of engaging roll 3, on mandrel 2. This position is illustratedfor description purpose only and may be altered without leaving thescope of this invention. The amount of wrap is not particularly limitedbut may advantageously be in the range from about 45 to about 315°, orfrom about 90° to about 300°, or from about 180° to about 270°, or about270° around the mandrel circumference. The more wrap, generally the moreaccurate the pitch control and/or the faster the apparatus can beoperated. While the orientation of the mandrel axis is shown ashorizontal, it could be vertical or some other desired orientation.While advantageous, the engaging rolls 3 and 4 are optional in thatwrapped engagement could be maintained by applying sufficient tension tothe profile layer 1. The advantage of the engaging rolls is that tensionbecomes a non-critical variable both at the profile layer spool 9 anddownstream of the mandrel beyond roll 3. When the wrapped portion of thematerials is engaged on the mandrel between rolls 4 and 3, the tensionbefore roll 4 and after roll 3 has no effect on the critical cord layingprocess which occurs in the wrapped portion. Thus, the tension can bechosen or optimized separately in the take-off zone and in thelamination and/or wind-up zones. There is no molding band in thecord-application zone of the wrapped portion. In particular theengagement roller 4 is not part of any molding band system.

The mandrel is rotated at a predefined speed for cord laying by a cordapplicator in the wrap portion of the mandrel. All the desired number ofcords are laid at the same time, preferably in a parallel, lengthwisearrangement. The cord spacing may be uniform or in any other arrangementdesired. FIG. 2 shows sixteen cords 7 merely as a representativeexample. The cords are let off of a creel 19 which may have any desirednumber of spools 8 (only four are shown in FIG. 1), and the cords areguided, for example, by guides 22 and 23, and/or tensioned, for example,by tension rolls 25 and/or 26, and finally fed into the cord applicatorrolls 6 and 24. In the embodiment shown, the cord applicator rolls 6 and24 are both electrodes which supply electricity to cord sections 7 a toheat them to a temperature suitable to melt the surface of the profilelayer when pressed therein by guide roll 6 at the desired depth tocontrol the pitch line of the belt. Then the materials quickly cool,fusing the cords to the profile layer 1 b to form reinforced carcass 27with partially embedded cords 7 b. Electrical heating is particularlyuseful for conductive cords such as steel cords or carbon fiber cords.For other types of cord materials, other heating means may be used, suchas hot air blowers, radiant heaters, and the like. According to anembodiment of the invention, the cord applicator includes a pair ofelectrodes for each cord, which may be grooved rollers over which thecords move, which supply sufficient current through the cord to heateach cords. The heat supplied may be enough to melt the profile layerand fuse the cords into the profile layer as the cords are brought intocontact therewith. Preferably, the heating of each cord is controlledindividually. The current may be supplied directly to isolated groovedroller electrodes by brushes, either internal or external, i.e., theelectrode rollers may be slip rings or like slip rings which transmitelectricity from a fixed to a rotating body. Alternately, the currentmay be supplied to the electrodes through the shaft and connected to thepower and control source by a separate slip ring device with sufficientcircuits for each cord. In another embodiment, the two electrode rollersmay be designed solely to transmit power to heat the cords, and a thirdroller used to apply the cords to the profile layer. Such a design wouldcorrespond to FIG. 1 if rollers 24 and 26 were the two electrodes androller 6 the applicator roller, for example.

According to another embodiment of the invention, also shown in FIG. 1,heated profile blades 5 are positioned against the back side of theprofile material to melt grooves into the profile material at a precisedepth, width and temperature. The heated blades 5 may have a profilededge which forms a groove on the back side of the profile layer 1 a.Then the tension members or cords 7 are provided from cord creel 19 andsupplied to the guide roll 6, which places the cord into the groove atthe desired depth to control the pitch line of the belt. The groovewidth and depth may be about the same as the cord diameter. The heatedblade preferably acts like a plow as it forms a groove of moltenmaterial. Cord guide roll 6 supplies cord 7 a, guides and presses itinto the groove before the groove material re-solidifies. The distancebetween blade and cord guide roll, cord lay speed, and temperaturesshould be controlled such that the TPE material stays molten until thecord is embedded. The result is reinforced profile 1 b with cord 7 bfused thereon, i.e. carcass 27.

According to another embodiment of the invention, the above heatingand/or groove-forming methods may be combined. Thus, the grooves may beformed by the heated profile blades, and the cord may heated beforeembedding or fusing. If the groove solidifies before the cord contactsit, then the heating of the cord should be sufficient to remelt thegroove surface to fuse the cord to the profile material. Alternately,the fusing of the cord to the profile material may be by means of atacky adhesive which may be applied to the cord earlier or during thecord application process.

In each embodiment, the heating and/or groove formation may becontrolled to allow variable speed cord laying, e.g. to accommodateinitial ramp-up or other speed changes. Also, the molten TPE or TPUmaterial of the profile layer may rapidly cool as the cord is embeddedinto it or before embedding as described above. Either way, the cordsare bonded to the profile material before the wrapped portion exits theengagement portion of the mandrel. The cord is thus partially embeddedand fused to the profile layer and is able to freeze the pitch of theteeth very accurately while the resulting reinforced carcass is stillengaged on the mandrel. The pitch is then accurately retained even whenthe carcass is disengaged from the mandrel because of the typically veryhigh tensile modulus of the cord. The heated blades are positioned apredetermined distance from the mandrel surface to control the cordposition against the profile surface for exact pitch-line control. As aresult, the cord position is not affected by irregularities in thicknessor surface waviness of the profile layer. The precise depth of thegroove and the precise placement of the cord results in a preciselycontrolled pitch line and PLD as is desirable particularly for toothedbelts. During cord laying the cords are also tensioned to a predefinedlevel to achieve the correct length and pitch of the belt. Cord feedapparatus 19 may thus include one or more spools or reels, associatedtensioning or braking apparatus and the like, as desired, and notnecessarily as illustrated in FIG. 1. Also, cord temperature may beincreased or controlled in the cord lay zone to remove moisture, toadjust or stabilize the melting and fusing effect, and/or to minimizethe effect of environmental conditions such as humidity or temperature.

It should be understood that by fusing the cords to make the carcass atthe desired PLD and tension, the portion of the reinforced carcass 27leaving the mandrel and proceeding through the lamination section doesnot require any particular tension to maintain cord spacing, cord laybelt pitch, or integrity of the carcass. This principle eliminates theneed to hold the carcass under a given tension when it is disengagedfrom the mandrel and makes the process simple and very effective inproductivity as well as in dimensional accuracy. Thus, a number of theproblems associated with prior art methods are eliminated. Reliance onbuilding the belt on a single mandrel for pitch (tooth spacing) controlrepresents a distinct advantage over prior methods which might have usedtwo or more profiled mandrels, allowing significantly lower cost andmore compact equipment design, providing higher material-, labor- andenergy-efficiency as well as more accurate product dimensions,particularly pitch control on long, endless, toothed belts. Some usefulamount of tensioning may of course be utilized advantageously to insureproper training of the belt through the lamination and windup sectionsas discussed previously.

It should also be understood that according to the present method, thecord is fully supported by the profile layer. This also represents adistinct advantage over prior methods which required small flights orprotrusions or noses on each tooth of the mandrel to lift the cord offof the mandrel surface for a desired PLD. Such flights resulted in cordbends which could weaken the cord or lead to early fatigue failure. Suchflights also resulted in cord exposure at the flight impressions in theland area in the finished belt, which could also be points ofcontamination and/or corrosion causing early belt failure. Theelimination of flights also allows the same apparatus to produce beltswith a variety of cord material types, cord diameters, and/or PLD.Conventional methods using flights normally required new mold tooling toaccommodate a change in the cord thickness. Also the use of certaintension member materials like glass fiber was not possible because theflights would damage such material during manufacture and operation ofthe belts. The invention allows the use of all types of tension memberson the same tooling by adjusting the position of the heated grooveprofiling device to control PLD. “Tooling” is used to refer to themandrel, i.e., a specialized mold limited (unless substantially altered)to making belts having the specific profile of the tool. The tooling ofthe present invention is much more versatile than in prior art methods.

Electrical heating of metal cords may be used to fuse it to thethermoplastic. The present invention, with a heated blade, normally doesnot require heating of the cord and can apply to all kinds of tensilecord materials. However, heating of the cord may allow an increase incord lay speed and can easily be provided by heating the cord before itenters the guide roll and/or heating the guide roll. Heating may beachieved electrically or with external heaters of any suitable type. Thecord may be embedded approximately 30% to 100%, or 50% to 90% or abouttwo thirds of its thickness or in the range from one-half to one corddiameter, but this may advantageously be adjusted, depending on thematerial of the cord and the profile layer and cord diameter, to give adesired PLD.

Some alternative groove-forming methods can be mentioned. Instead of theheated knife, laser cutting or profile grinding could be applied to formthe groove in which to lay the cord. Alternately, mechanical knifecutting could be used in combination with laser heating, or infraredheating, or hot air, or the like. The grooves could be formed directlyin front of the cord roller as discussed above. Alternately, the groovescould be formed in a separate operation over the whole profile layerprior to cord laying. In the latter case, if the groove is formed offline, the groove surface would be heated to melt it just before the cordis laid into the groove to achieve the required fusion of the cord tothe profile material, or the cord could be heated and applied, or anadhesive could be used to fuse the cord in the groove.

After completion of the cord laying operation, top layer material 10 isapplied to reinforced carcass 27 by passing the carcass through alaminator or laminating zone. The laminator illustrated in FIG's 1 and 2includes pressure rolls 13 and 14 with a nip there between. Top layer 10and reinforced carcass 27 form a nip where the two materials, partiallymolten by lamination heater 11, are pressed and joined together formingbelt 20. Belt 20 may be taken up on spool 15. The process parameters oflamination speed and heat input should be adjusted such that only a thinskin of melting occurs on both surfaces without the material meltingthrough and loosing its shape. Even pressure along the whole length ofthe laminating rolls is also advantageous and may be facilitated by useof an elastomeric roll, although steel rolls provide better heattransfer. The optimum heating and melting amount permits the top layerto fully bond to the carcass and cord, flowing around the portion of thecord not yet embedded, but not disturbing the pitch line and position ofthe cord.

According to an embodiment of the invention, FIG. 4 shows the laminatorintegrated onto the mandrel 2, which saves space overall. In FIG. 4, themandrel 2 and pressure roll 43 form the nip for pressing top layer 10onto the reinforced carcass somewhere past the cord lay zone but stillin the wrap portion of the mandrel. Heater 41 again supplies energy tomelt the surface or surfaces for fusing together the top layer andcarcass. The belt itself then is disengaged from the mandrel atengagement roller 3 and proceeds to optional finishing operations andwind up (not shown).

According to another embodiment of the invention, the laminator may usea pressure or molding band which may wrap around a portion of themandrel, which provides longer residence time for fusing the top layerto the carcass. FIG. 5 illustrates a molding band arrangement whereinthe lamination takes place directly on the mandrel after the cord isapplied. Pressure band 52 is trained around rollers 53, 54 and 55.Tension may be maintained on the pressure band with a tension roller 56.Alternately, roller 56 may not be needed if roller 55 has tensioningcapabilities. Profile layer 10 (not shown) may be introduced to the nipbetween pressure band 52 and mandrel 2 located at pressure roll 53,analogous to FIG. 4. Heat may be applied just as in FIG. 4. Roller 54may be part of the molding band system and function as the engagementroller 3 in FIG. 1 or 4. Alternately, a separate roller (not shown) maybe used for disengaging the belt from the mandrel. The pressure bandcould have a surface texture or pattern in order to introduce a desiredtexture to the top layer, i.e. to the backside of the belt.

According to another embodiment of the invention, with a pressure bandin place, also shown in FIG. 5, a fluid metering nozzle 51 may be usedto apply liquid material 59 to form the top layer 10 within the cavitydefined between a portion of the pressure band 52 a and the mandrel 2.Instead of laminating directly on the mandrel, the pressure bandlaminator may be positioned down stream in a way analogous to thelaminator location in FIG. 1. Then the pressure band would wrap around asecond pressure roll (like pressure roll 14 in FIG. 1), instead ofaround mandrel 2. In either case, flanges on the ends of mandrel 2 orroll 14 may be used to seal the edges of the corresponding moldingcavity to prevent liquid material from oozing out. The liquid materialmay be molten thermoplastic such as TPE or TPU material. The liquidmaterial 59 may be a curable liquid such as liquid silicone resin,castable polyurethane, or the like. The metering nozzle 51 may includean extruder for thermoplastic materials, or a gear pump for curableliquid resins, or other appropriate device or devices. Any suitableresin may be used provided suitable adhesion is achieved with thecarcass. Foaming resins may be used to achieve a desired compressibilityor softness of the top layer. A textile layer could be applied to thecarcass to be embedded between the carcass and the top layer.

In another embodiment utilizing a resin casting option, the cast resinmay be applied onto the carcass without a pressure band and curedwithout external pressure. Any suitable resin may be used providedsuitable adhesion is achieved with the carcass. Foaming resins may beused to achieve a desired compressibility or softness of the top layer.Edge flanges on the mandrel may be useful to prevent liquid resin fromflowing off the mandrel before curing. Typically, the surface will thenneed to be ground or trimmed to achieve a final smooth surface and abelt of uniform thickness.

Another method to apply the cord and provide lamination in one operationis proposed by using a mini-extruder which has a die which is designedfor coating cords 7 to guide the cord through and apply the TPU or TPEmaterial around it sufficient in quantity and shape to provide the cordlay and the lamination material for this section at the same time. Thenthe lamination material is applied along with the cord laying. Theextrusion part of this method is similar to a cable pultrusion process,which provides a further improvement to speed and cord embedding. Thismethod may be applied in combination with the groove cutting blades orwithout them. This method may be applied with a pressure band orwithout.

After manufacturing the belt, the same process may be adapted and usedto grind the surface of the backside or to otherwise machine the sleeveto provide a smooth or specific designed pattern on the back surface.Optionally or in addition, the back surface of the sleeve can belaminated with a fabric and method described for example to providespecific friction, wear or noise characteristics. Finally the belt maybe printed or labeled and/or cut into a desired belt width whilerotating on, installed on, or otherwise using, an embodiment of the sameapparatus.

The method and apparatus also allows one to apply cord onto a carcasswide enough for multiple belts leaving plenty of space free of tensionmember between each belt. This space facilitates the cutting of thebelts, and results in belts with no cord exposed on the cut edge, i.e.no “edge cord.” The result after lamination and cutting will be openended belts with no exposed edge cord and no exposed cord due toflights. In other embodiments, different materials can be used on theprofile (e.g., for enhancing noise or load performance) and on top side(e.g., for friction, appearance, profiling or the like). Likewise,textile or fabric can be used on the profile and/or on the backside. Thebackside can also be profiled instead of smooth. For example, the beltcould then be a two-sided timing belt, or a timing/V-belt combination,or a multi-ribbed v-belt that is single- or double-sided. Alternately,the belt could be a flat belt, or have some other specific profile orprofiles.

Suitable controls can be provided for automation of the inventiveapparatus and method. For example, automatic control can be applied toengage, rotate and/or disengage various rollers such as the mandrel,guide rollers, laminating roller, cord guide roll and heating blade, andthe like. Automatic control can be applied to control the temperatureand/or energy input of the heating blade, the lamination heater and thelike. Automatic control can be applied to various optional associatedfinishing processes such as grinding, machining, labeling, cutting, andthe like. The control algorithms can be implemented in software and/orhardware. Manual intervention or manual operation can be provided for asdesired.

The open-ended belt may be cut to a desired length and joined by knownmethods to form an endless belt, and in the case of a toothed belt, withthe desired number of teeth. Fusion of the ends may be, as non-limitingexamples, by thermal fusion by heat treatment or ultrasonic welding,direct adhesion, or thin film or adhesive tape, or clamps, with buttjoint or finger joint, or combinations thereof.

A number of additional advantages of the invention may be noted. Byeliminating both flights and edge cord, the belt may be wholly sealedfrom the intended use environment as may be required for food service orother “clean belt” applications requiring cleaning, sterilization or thelike. Also, the fully encapsulated tension member will be betterprotected against corrosion and bending, resulting in significantservice life improvement. Thus, more expensive corrosion resistant steelwires (e.g. zinc-coated wires) may be replaced with more economical(e.g. not zinc-coated) steel wire.

Separate manufacture of the profile material and the top layer materialhas a number of advantages over prior methods where everything wasformed and assembled on the same apparatus. Separate manufacture allowsprofile and top layer materials to be made at optimum speeds forextrusion, generally much faster than possible when cord laying and/orlaminating is done at the same time. Separate manufacture also permitsmuch easier set up of the belt making system of FIGS. 1 and 2, and for amuch simpler design of that apparatus and lower capital cost. Inparticular, a complicated extruder with crosshead die for multiple cordsand a conventional molding pressure band and its associated drive systemare not necessary. Set up times may be significantly reduced and cordmaterial utilization may be improved.

The inventive method includes snugly fitting the profile material 1 ontothe mandrel 2 during cord lay by means of the engaging roll 4. In oneembodiment, the teeth of the profile layer of the wrapping portion ofthe profile material are snug fit into the mating grooves of the mandrelin the wrapping portion. This snug fit, along with precision machiningof the mandrel profile, and in conjunction with the control of the cordposition, helps to insure consistent control of the pitch and pitchlength of the resulting belt. It is advantageous to make the endlessprofile layer initially a little shorter in pitch than the final belt,to ensure the profile layer is stretched to hold the tight fit on themandrel rather than compressed as it would be in the case where theprofile layer pitch is longer than the nominal pitch of the mandrel. Itis the mandrel and the cord lay process that controls the ultimate beltpitch and pitch length for a toothed belt.

It may be noted that when the inventive methods are applied to makingflat belts, or profiled belts that are not intended for synchronizingwith toothed pulleys, the PLD and/or pitch tolerance(s) is generally notso critical as for toothed synchronous belts. Moreover, throughout thisdescription, the distinction between profile layer and top layer may bearbitrary, so that the final belt may be considered made upright orinverted. Thus, the profile layer described herein may be flat and thetop layer may include a profile. Note that if the profile layer is flat,then the wrapped engagement of the profile layer on a wrap portion ofthe mandrel during rotation of the mandrel may be essentially frictionalengagement which may be aided by engaging roll 4 and take-off roll 3.

Other variations of the inventive methods within the scope may bementioned. According to one variation, the profile material may beformed directly on the profiled mandrel by extruding or metering profileor matrix material onto the mandrel, for example with a pressure band inplace like the one shown in FIG. 5. According to another variation, thecord may be applied to the top layer using methods analogous to thosedescribed herein for laying and fusing cord to the profile layer. Thenthe carcass (i.e., the flat top layer with applied cord) may belaminated to the profile layer. This variation may be applied to any ofthe various embodiments described herein. In another variation, the cordlaying step may be added to the step of forming the profile layer or thetop layer, as the case may be. Then the lamination step may be performedseparately.

FIG. 6 illustrates a variation on the method and apparatus in which theprofile material 1′ is formed directly on the profiled mandrel 2 byextruding or metering at 51 the profile or matrix material onto themandrel, using pressure band 52 which is guided around by rolls 53-56like the one shown in FIG. 5. Although cord 7′ could optionally beapplied at 6′ (as shown in dashed lines and analogous to the apparatusof FIG's 4 or 5), in this case, cord 7 is already affixed to top layer10 which is fed from spool 12 into laminator roll 43 where heater 41 isused to fuse the two layers and embed the cord therein. Finished belt 20then comes off the mandrel at take-off roller 3.

FIG. 7 and FIG. 8 illustrate another embodiment of the process. In afirst step shown in FIG. 7, cord(s) 7 are laid onto a smooth mandrel 2′and then coated with matric material from extruder 51 which is thencooled under the pressure band 52 to form carcass 77, which is a flatfilm with cord embedded right at the surface. The cords may be multipleparallel cords as described for other embodiments. Extrusion and thepressure band section may also be as described in other embodiments,such as FIG. 5. In a second step, shown in FIG. 8, profile mandrel 2replaces smooth mandrel 2′, in order to make a profiled belt 20. Ofcourse, the smooth mandrel may be used again if a flat belt is to bemade. The extruder and pressure band section are now used to form theprofile layer while the flat carcass 77 is fed into the pressure bandsection at the same time. Thus, the flat carcass, containing the tensilecord, is laminated to the profile layer as the profile layer is formed.The surface of the carcass at which the cord is just embedded ispreferably placed against the profile layer to seal the cord therein.The first step is found to provide a flat film with very good control ofthe cord position, since the cord is laid on a smooth mandrel. Theresulting belt 20 has very good cord control, and the PLD may easily becontrolled by the positioning of the pressure band. According to anothervariation, this two-step process could be carried with a laminating rollsuitable arranged close to the mandrel or forming roll, instead of thepressure band shown in the figures.

It should be noted that in the first step, FIG. 7, the cord crosssection may flatten somewhat on the smooth mandrel. Then the cord mayspring back after the carcass is removed from the mandrel, resulting ina flat carcass with cord slightly protruding from one surface instead offully embedded. So the cord may be mostly embedded in the carcass. Stillin the final belt, the cord will be embedded between the layers.

Thus, the embodiment of FIGS. 7 and 8 relates to a method of making anopen-ended, reinforced, layered belt including the steps of: (i)training a plurality of parallel tensile cords on a portion of a smooth,rotating, cylindrical mandrel, the portion including a cavity definedbetween the mandrel and a molding band or a gap defined between themandrel and a laminating roller; (ii) extruding a top layer materialonto the cords and metering it into the cavity defined between themandrel a molding band or into the gap defined between the mandrel and alaminating roller; thereby forming a carcass comprising the cordsembedded at one surface of a film of the top layer material; (iii)training the carcass on a portion of a profiled, rotating, cylindricalmandrel having a profile complementary to a desired belt profile, theportion including a cavity defined between the profiled mandrel and themolding band or a gap defined between the mandrel and the laminatingroller, and the one surface facing the profiled mandrel; and (iv)extruding a profile layer material onto the profiled mandrel between thecarcass and the mandrel surface and metering it into the cavity or intothe gap; thereby forming the belt comprising the cords embedded betweenthe top layer material and the profile layer material.

According to other variations of the process, the profile layer may bemade from a flat layer by welding teeth or other profile features to asurface of the flat layer. This may be done off line in a separate stepor on the apparatus described herein in continuous fashion. Alternately,this or many of the other variations described above could be achievedby two or more passes of material(s) through the apparatus. A firstpass, for example, could make the carcass, whether toothed or flat. Asecond pass could form and/or laminate a top layer onto the carcass.Another pass could weld or glue or fasten on profile parts, such as beltteeth for driving the belt on pulleys, or other objects, profiles,holders or such features which might ultimately be used for transportingitems or material handling or the like.

According to various embodiments of the invention, it is possible toproduce long length belting ranging from 10 inches to 50 inches or morein width, preferably greater than 18 inches, or greater than 24 inches,or greater than 36 inches in width. Belts wider than about 24 incheshave not been practical using conventional methods, e.g. withcomplicated crosshead extrusion dies. It has been shown via belt testson T10 profile TPU belts using a DeMattia flex fatigue tester that beltswithout flights or nose regions can out-perform commercial belts withflights by a factor of about 10. Thus, a significant improvement inperformance over conventional open-ended belting may be obtainedaccording to the inventive methods. Thus, the cord is totallyencapsulated, i.e., not exposed except at a cut cord end at the end ofan open-ended belt.

The invention systems and methods described herein could also be used tomake tracks for use in track drive systems for various types oftrack-driven vehicles, including without limitation, snowmobiles, snowcats, and other transportation vehicles, military vehicles, constructionvehicles, robots, and the like. Examples of such an endless track aredisclosed in U.S. Pat. No. 3,338,107 to Kiekhaifer, U.S. Pat. No.8,033,619 to Bellemare, and U.S. Pat. No. 7,090,312 to Soucy et al., thecontents of which are hereby incorporated herein by reference. The trackmay have a series of internal drive lugs, which may be formed andengaged on the mandrel in a way analogous to the teeth on a toothedbelt, as described herein. Likewise, the track may have a series ofexternal traction lugs, which may be formed in way analogous to theteeth on a dual toothed belt as also described herein. The track may becut to a desired length and joined by known methods to form an endlesstrack. In other embodiments, the track may include a base belt formedwith the invention systems and methods described herein after whichinternal and/or external lugs are fastened thereon.

Although the present invention and its advantages have been described indetail, it should be understood that various changes, substitutions, andalterations can be made herein without departing from the scope of theinvention as defined by the appended claims. Moreover, the scope of thepresent application is not intended to be limited to the particularembodiments of the process, machine, manufacture, composition of matter,means, methods, and steps described in the specification. As one ofordinary skill in the art will readily appreciate from the disclosure ofthe present invention, processes, machines, manufacture, compositions ofmatter, means, methods, or steps, presently existing or later to bedeveloped that perform substantially the same function or achievesubstantially the same result as the corresponding embodiments describedherein may be utilized according to the present invention. Accordingly,the appended claims are intended to include within their scope suchprocesses, machines, manufacture, compositions of matter, means,methods, or steps. The invention disclosed herein may suitably bepracticed in the absence of any element that is not specificallydisclosed herein.

What is claimed is:
 1. A method of making an open-ended, reinforced,layered belt comprising; training a plurality of parallel tensile cordson a portion of a smooth, rotating, cylindrical mandrel, said portionincluding a first cavity defined between said smooth mandrel and amolding band or a first gap defined between said smooth mandrel and alaminating roller; extruding a top layer material onto said cords andmetering it into said first cavity or into said first gap; therebyforming a carcass comprising said cords embedded at one surface of afilm of said top layer material; training said carcass on a portion of aprofiled, rotating, cylindrical mandrel having a profile complementaryto a desired belt profile, said portion including a second cavitydefined between said profiled mandrel and said molding band or a secondgap defined between said profiled mandrel and said laminating roller,and said one surface facing said profiled mandrel; extruding a profilelayer material onto said profiled mandrel between said carcass and saidprofiled mandrel surface and metering it into said second cavity or intosaid second gap; thereby forming said belt comprising said cordsembedded between said top layer material and said profile layermaterial.
 2. The method of claim 1 wherein said top layer material andsaid profile layer material both comprise thermoplastic elastomer orthermoplastic polyurethane.
 3. The method of claim 2 wherein said belthas no exposed cord portions except cut cord ends.
 4. The method ofclaim 1 wherein said profiled mandrel is a grooved mandrel and said belthas a toothed or ribbed profile formed by the grooves.
 5. The method ofclaim 1 wherein said carcass is relaxed before said training saidcarcass.
 6. The method of claim 5 wherein said cord is slightlyprotruding from said one surface of said carcass before said trainingsaid carcass.
 7. The method of claim 5 wherein said cord is mostlyembedded at said one surface of said carcass before said training saidcarcass.
 8. The method of claim 1 wherein said method comprises twopasses through a single apparatus comprising said molding band or saidlaminating roller.
 9. The method of claim 8 wherein the first of saidtwo passes comprises said steps of training a plurality of paralleltensile cords and extruding a top layer material, and the second of saidtwo passes comprises said steps of training said carcass and extruding aprofile layer material.
 10. The method of claim 9 wherein said smoothmandrel is used in said single apparatus for one of said two passes andsaid smooth mandrel is replaced by said profiled mandrel in said singleapparatus for the other of said two passes.
 11. A method of making anopen-ended, reinforced, layered flat belt comprising; training aplurality of parallel tensile cords on a first portion of a smooth,rotating, cylindrical mandrel, said first portion including a firstcavity defined between said smooth mandrel and a molding band or a firstgap defined between said smooth mandrel and a laminating roller;extruding a top layer material onto said cords and metering it into saidfirst cavity or into said first gap; thereby forming a carcasscomprising said cords embedded at one surface of a film of said toplayer material; training said carcass on a second portion of saidsmooth, rotating, cylindrical mandrel, said second portion including asecond cavity defined between said smooth mandrel and said molding bandor a second gap defined between said smooth mandrel and said laminatingroller, and said one surface facing said smooth mandrel; extruding aprofile layer material onto said smooth mandrel between said carcass andsaid smooth mandrel surface and metering it into said second cavity orinto said second gap; thereby forming said flat belt comprising saidcords embedded between said top layer material and said profile layermaterial.
 12. The method of claim 11 wherein said carcass is relaxedbefore said training said carcass.
 13. The method of claim 12 whereinsaid cord is slightly protruding from said one surface of said carcassbefore said training said carcass.
 14. The method of claim 12 whereinsaid cord is mostly embedded at said one surface of said carcass beforesaid training said carcass.
 15. The method of claim 11 wherein saidmethod comprises two passes through a single apparatus comprising saidsmooth mandrel and said molding band or said laminating roller.
 16. Themethod of claim 15 wherein the first of said two passes comprises saidsteps of training a plurality of parallel tensile cords and extruding atop layer material, and the second of said two passes comprises saidsteps of training said carcass and extruding a profile layer material.